1. Field of the Invention
This invention relates to a disc apparatus used as an external recording, reading, and memory means in a computer system, a word processor, or the like.
In such a disc apparatus, the access time required for a disc head to access a predetermined track of the disc media must be reduced, and further, it must possible to easily and rapidly replace, change, or repair the parts used in the disc apparatus, since various changable parts, such as a laser diode, are used in the disc apparatus.
2. Description of the Related Art
FIG. 8 is a perspective view of a stationary type optical disc apparatus known in the prior art, in which a plurality of (e.g., eight) optical disc media 10 are arranged in parallel while spaced equidistantly from each other and supported on a spindle 16, and these optical discs 10 are integrally rotated by, for example, a spindle motor 11.
At the respective sides of the optical disc media 10 are provided optical heads 15, each of which is mounted on a carriage 12 movably mounted on rails 14 on another carriage 13, so that the optical head 15 on the carriage 12 can be moved in the direction of the faces of the optical disc media 10. The carriage 13 is movably mounted on rails 17 arranged in parallel to the spindle shaft 16 of the optical discs 10, and thus all of the parts, including the optical head 15 mounted on the carriage 12, can be moved in parallel to the spindle shaft 16 over the plurality of optical disc media 10.
As mentioned above, the pair of optical heads 15 each including an accessing mechanism have the same structure and are arranged symmetrically at the left and right sides, respectively; one of the optical heads being used as a backup for the other optical head.
When the optical head 15 is to be moved from one of the optical disc medium 10 to another predetermined optical disc medium 10, the optical head 15 is first moved along the rail 14 on the carriage 12, to be retracted from the region of the optical disc media 10, and after having been completely retracted, the carriage 13 is then moved along the rail 17, so that the optical head 15 comes to a position corresponding to the predetermined optical disc medium 10. The optical head 15 is then moved along the rail 14 on the carriage 12 to enter a predetermined position on the surface of the optical disc medium 10.
According to the above-mentioned stationary type optical disc apparatus, when the optical head 15 is to access another optical disc medium 10, the optical head 15 must move not only in the direction parallel to the disc surface, for retracting and entering, but also in the direction parallel to the spindle shaft 16 over the disc media 10. Therefore, according to the above-mentioned optical disc apparatus known in the prior art, the access time for the optical head is increased, and therefore, a high speed processing of the optical disc apparatus cannot be attained.
Also, since various changable parts, such as a laser diode (LD), are used in the stationary type disc apparatus known in the prior art, such parts must be regularly changed, but an easy and rapid replacing, change, or repair of the parts is prevented because the optical head and the accessing mechanism thereof are complicated, as mentioned above.
Particularly, in the known disc apparatus, when the laser diode (LD) is to be changed or repaired, the optical head has to be removed from the optical disc apparatus and the laser diode has also to be removed from the optical head. At the same time, an axis of the optical path of the laser diode and circuit elements for controlling the power of the laser diode have to be regulated. Such regulations take laborious works.